苜蓿中华根瘤菌共生固氮相关基因突变体的分离和鉴定
Isolation and identification of mutant of symbiotic nitrogen fixation related genes from Sinorhizobium meliloti

为了阐明豆科植物共生反应与免疫反应的协调机制，揭示参与植物细胞侵染、定殖及固氮过程中根瘤菌基因的功能，以苜蓿中华根瘤菌Sm2011为材料，构建了约8 000株Tn5 sacB转座子插入的突变体库。利用巢式PCR检测技术，从中鉴定和筛选出nodC、nifH、smc01188和smc04024等4个特定目标基因的插入突变体及其插入位点。通过结瘤试验考察突变体共生及固氮表型，结果显示：植株接种smc01188突变体28 d后，与对照植株相比，该基因突变导致根瘤固氮酶活下降，与慢生型大豆根瘤菌该基因突变体的表型类似; smc04024基因突变不影响植株生长，根瘤发育基本正常；接种nifH突变体后，植株呈缺氮表型，生长发育受阻，根瘤为白色；接种nodC突变体后植株不结瘤，说明Tn5 SacB的插入导致nifH、nodC基因功能丧失。利用PCR检测、鉴定和分离目标基因突变体是一种行之有效的方法。
Phosphorus is an important element required for plant growth. The absorption and transportation of Pi are carried out by phosphate transporter in legumes. In this paper,phosphate transporter AsPT6,a new member of pht1 family,was identified in Astragalus sinicus. AsPT6 was expressed in leaves,stems and roots. The expression of AsPT6 was increased significantly in the roots and nodules when inoculated with Mesorhizobium huakuii 7653R. The results of tissue localization showed that AsPT6 was expressed in the vascular tissue of roots,nodules,and the junctions between root and nodule,indicating that AsPT6 may play a role in transporting phosphate from the root to nodule. Overexpression and RNA silence of AsPT6 significantly affected the nodulation and nitrogenase activity of nodules. It is indicated that AsPT6 is involved in the transportation of phosphorus during the formation and development of nodules.